Impact-absorbing helmet

ABSTRACT

The invention relates to a helmet that includes an outer shell and a cap, the cap being comprised of a material such as EPS or EPP and arranged inside the shell. The shell has an upper portion designed to cover at least the crown portion of the skull, the cap further comprising a first layer having a thickness covering substantially the upper portion and a plurality of pads of height projecting from the first layer towards the head, the first layer and the pads forming a single piece, and the height of the pads being greater than the thickness of the first layer.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon French Patent Application No. 14/01633, filed Jul. 18, 2014, the disclosure of which is hereby incorporated by reference thereto in its entirety, and the priority of which is claimed under 35 U.S.C. §119.

BACKGROUND

1. Field of Invention

The invention relates to a protective helmet for sporting activities. Such activities may in particular include alpine skiing, ski touring, or snowboarding. The invention also extends to the practice of rock climbing, mountaineering, cycling, and snowmobiling. Generally, a helmet provides head protection to protect the skull from impacts to which it may be subjected when the user falls, when an object is thrown at the user, or in a collision with an object or another person.

2. Background Information

A conventional helmet construction includes an outer shell and a cap. The outer shell is generally rigid and, as an example, is made by molding/injection of a thermoplastic material such as ABS (Acrylonitrile Butadiene Styrene) or PC (polycarbonate). Typically, the cap is made of a foam material such as EPS (Expandable Polystyrene) or EPP (Expandable Polypropylene). To ensure good user comfort, the helmet is generally provided with an inner cap that, for example, can be made of foam covered with fabric. The inner cap is attached to the inside of the cap.

A helmet is designed to reduce the risk of injury in the area of the skull of the user, while having the smallest possible weight in order not to affect the comfort of the user.

Therefore, a good helmet should meet two conflicting requirements, namely, to contain as much damping material as possible, on the one hand, and to be as lightweight as possible in order to be easily portable and not impede the user.

To ensure the safety of users, there are several standards generally defining tests and acceptance thresholds that are applied to helmets requiring certification in a related discipline. The normative requirement may differ, depending on the sporting activity. Thus, a standard covers a specific activity. These requirements give rise to characteristics that the helmet must have to provide the required protection. For example, depending on the activity practiced, these characteristics correspond to properties of resistance to penetration and shock absorption in various zones of the helmet.

Thus, there appears to be a strong need to design a helmet having good damping in its crown portion, as this zone is often critical for successfully passing the tests for homologation.

In this zone, the helmet damping characteristics depend mainly on the design of the cap.

The most common cap construction is in the form of a casing assuming the morphology of the skull. Achieving the desired damping requires using suitable materials and/or varying the thickness of the casing, which results in a dimensioning that can weigh down the helmet, thus creating a source of discomfort for the user.

Other constructions propose attaching independent pads directly to the outer shell (see U.S. Pat. No. 4,766,614), to an inner shell (see GB 2 240 255; U.S. Pat. No. 4,239,106), or associating them with the inner cap (see U.S. Pat. No. 7,774,866; EP 0 423 379). In any case, these pads are dimensioned to operate in compression. Damping is thus obtained by compressing the pads. In certain embodiments, the pads are used to wedge the head. These various constructions, incorporating attached pads, are complex and expensive to produce. One difficulty relates to fixing and maintaining the pads on the helmet.

Another construction provides for a cap fitted with ventilation channels defining projections projecting toward the head of the user. This type of structure is characterized by a cap having a relatively thick layer from which the projections extend along a small height. Damping is achieved here by the thick layer, the projections having the role of channeling the flow of air providing ventilation at the top of the skull. In this construction, to obtain the desired properties, the projections have a height less than the thickness of the cap. The document EP 2 716 175 illustrates this type of helmet.

SUMMARY

The invention provides an improved helmet.

In particular, the invention provides a lightened helmet structure having good damping properties.

The invention also provides a helmet, the structure of which includes few assembled constituent elements.

The invention further provides an economical helmet, the implementation process of which is simple.

To these ends, the invention provides a helmet comprising:

-   -   an outer shell;     -   a cap, made of a material such as EPS or EPP, for example, the         cap being arranged inside the shell and having an upper portion         designed to cover at least the crown portion of the wearer's         head, the cap comprising a first layer of thickness “e” covering         substantially the upper portion and a plurality of pads of         height “h” projecting from the first layer towards the head, the         first layer and the pads forming a single element.

The height of the pads of the helmet is greater than the thickness of the first layer.

This structure makes it possible to have, with few parts, a cap attached to an outer shell, a lightweight helmet with good damping characteristics. This construction enables good anchoring of the pads on the cap, and the height of the pads allows for bending and/or buckling deformation, which improves the damping properties of the helmet. In addition, the helmet is compact and strong. A helmet according to the invention is lightweight and ventilated due to this specific construction. It also allows for the use of a simple, removable inner cap that can easily be replaced.

Optionally, the invention can have any of the following optional features, taken alone or in combination:

-   -   The thickness “e” of the first layer is between 1.0 mm and 17.5         mm.     -   The height “h” of the pads in the upper portion is between 10 mm         and 35 mm.     -   The average cross section of the pads is between 0.5 and 5.0         square centimeters.     -   A plurality of the plurality of pads of the upper portion are         dimensioned so that their height “h” is greater than the         smallest dimension characterizing the average cross section of         the pads.     -   The pads are distributed randomly in the upper portion.     -   The tops of the pads are designed to be in contact with the head         of the wearer or an inner cap covering the head.     -   The pads have a substantially parallelepipedic shape.     -   The cap is a monolithic element, that is, it is made of a single         piece of material.     -   The cross section of the base of the pads is substantially the         same as the cross section of the top of the pads.     -   The pads are oriented so that their height extends substantially         along a vertical direction.     -   The cap is made by molding.     -   The pads are recessed.

BRIEF DESCRIPTION OF DRAWINGS

The invention will now be described by way of non-limiting exemplary embodiments, with reference to the annexed drawings, in which:

FIG. 1 is a perspective view of a main embodiment of a helmet according to the invention;

FIG. 2 is a perspective bottom view of the interior of the helmet;

FIG. 3 is a bottom view of the helmet;

FIG. 4 is a cross-sectional view along the line IV-IV of FIG. 3; and

FIGS. 5 to 6 are partial cross sections showing various deformation modes of the pads of the invention.

DETAILED DESCRIPTION

The helmet 10 comprises an outer shell 11, a collar 12, a cap 13, cushions 14 for protecting the ears, and a chin strap 15.

The following description makes use of terms such as “horizontal”, “vertical”, “longitudinal”, “transverse”, “upper”, “lower”, “top”, “bottom”, “front”, “rear”, “anterior”, “posterior”. These terms should be interpreted as relative terms with respect to the position that the helmet occupies on the head of a user in normal posture, and the normal advance direction of the wearer.

The helmet comprises an upper portion 101 designed to cover at least the “crown portion” of the skull, that is to say, the top of the skull. It is defined by a zone covering an upper portion of the frontal bone and an upper portion of the parietal bone. In this example, this upper portion 101 of the helmet is comprised of an upper portion 111 of the outer shell and an upper portion 131 of the cap.

The outer shell 11 is monolithic, that is to say, made in a single piece. Here, it is made of polycarbonate (PC). Alternatively, it is made of acrylonitrile butadiene styrene (ABS), or a material embedded with carbon fibers or natural fibers. The outer shell 11 is molded, such as by injection molding, for example.

The cap 13 here is also monolithic. It is made of expanded polystyrene foam (EPS, i.e., Expandable Polystyrene). Alternatively, it can be made of expanded polypropylene (EPP, i.e., Expandable polypropylene), or other material, such as a foam material. It is fixed to the outer shell 11 to cover an inner surface 112 of the outer shell 11.

The cap 13 is designed to also wrap the head of the user. The construction of its inner envelope is described in greater detail, below.

The cap 13 can be an element separate from the outer shell 11, and assembled to the outer shell 11. Alternatively, it can be overmolded onto the outer shell 11; reference can be made to so-called thermoforming or “in-mold” technology.

To improve comfort, the outer shell 11 and the cap 13 can include openings positioned opposite one another so as to enable the inlet and/or discharge of a flow of air ensuring ventilation for the head of the user.

In this example, the lower portion of the helmet is demarcated by the collar 12 fixed to the cap. This collar concurrently marks the lower edge of the outer shell 11 and the lower edge of the cap 13. The collar 12 is optional, the invention also being applicable to helmets with no collar demarcating the lower edge of the helmet.

The cap 13 has a structure comprising two levels in the thickness direction.

The first level forms a first layer 132 of thickness “e” covering the skull of the user. This first layer substantially assumes the shape of the outer shell 11. The outer surface 1321 of the first layer 132 is fixed to the inner surface 112 of the outer shell 11. This assembly can be achieved by gluing, melting, overmolding, or other technology. The thickness “e” of the layer 132 is not necessarily constant over the entire inner surface of the helmet. For example, the thickness can be greater on the upper portion of the cap 13 and less on the lower portion, namely, the frontal, lateral, and posterior portions. As mentioned above, the first layer 132 can include openings for ventilation of the skull.

The second level of the cap structure comprises a set of projections 133, 134 projecting from the inner surface 1322 of the first layer 132 toward the head of the user. The shape of these projections varies as a function of their positioning.

In the lower portion of the cap (the frontal, lateral, and posterior portions), the projections form blocks 134, for example parallelepipedic blocks having a variable thickness. Thus, each block is thin in its lower portion and thicker in its upper portion. The blocks are evenly distributed on the lower inner periphery of the cap 13. Channels are thus formed between the blocks. These channels are used for circulation of air for ventilation of the skull.

The projections form pads 133 in the upper portion 131 of the cap (crown portion). In the illustrated example, these pads have a parallelepipedic shape, or a substantially parallelepipedic shape, having a substantially constant height “h”. However, these parallelepipeds have a variety of different cross sections, in relation to one another. In an alternative embodiment, they can have identical cross sections. Alternatively, the pads can assume other polyhedral or cylindrical shapes. They can be truncated pyramids, cylinders, truncated cones. Similarly, the height of these pads is not necessarily constant. Thus, one can provide zones in which the height of the pads is greater in order to increase damping, for example. Here again, channels are formed between the pads. These channels are used for circulation of air for ventilation of the user's head. According to the illustrated embodiment, the distribution of the pads is random in the upper portion 131. Alternatively, such distribution can follow a regular pattern.

The total thickness “T” of the cap 13 corresponds to the sum of the thickness “e” of the first layer and the height “h” of the projections, blocks 134, or pads 133. The total thickness “T” can vary depending on the portions of the cap involved.

In the upper portion 131 of the cap, most of the pads have sufficient height to obtain a deformation in addition, or as an alternative, to the compression of the pad, in order to improve the damping properties of the helmet. This deformation can be obtained via buckling or bending. In this case, the pads are dimensioned and arranged so that, not only can they be compressed, they can also be deformed in a non-axial direction. Thus, the pads do not deform only by compression as in most of the prior art constructions.

FIGS. 5 and 6 illustrate examples of deformations of the pads following an impact materialized by the vector “F”. The pad 133, biased by the force “F” comes pressing against the skull or the inner cap, represented here by the plane “P”. The pad 133 then deforms, first in compression, and then along a non-axial direction, due to its dimensioning. In FIG. 5, the deformation is similar to buckling. In FIG. 6, the deformation is similar to bending. The deformation of the pad can vary from one pad to another depending on the impact zone and the dimensions of the pad. It is not necessary that all pads meet the recommended ratio, as the impact can be absorbed by a few pads. The damping properties are nevertheless better if a number of pads have a height greater than the thickness of the first layer.

To obtain this additional or alternative deformation, the proposed construction includes sufficient anchoring for the base of the pads and a height of the pads enabling this additional deformation. The first layer 132 of thickness “e” thus makes it possible to affix the pads to one another to create a unitary and homogeneous structure. Moreover, in order to obtain a satisfactory deformation, the height “h” of the pads is greater than the thickness “e” of the first layer.

Furthermore, to obtain an even more efficient additional or alternative deformation, certain pads positioned in deformation zones have a height “h” greater than the smallest dimension characterizing the average cross section of these pads. The smallest dimension can be a side of a square or rectangular cross section, the smallest height or length of a parallelogram-shaped cross section, the diameter of a cylinder. The greater the height in relation to this dimension, the easier the desired additional deformation will be. The pads can then more easily deform along a non-axial direction.

According to an embodiment having good damping, the cross section of the base of the pads is substantially the same as the cross section of the top of the pads. Therefore, pyramidal or overly tilted cone-shaped pads can be avoided so that the pad does not essentially become deformed in compression, which is not the desired behavior.

Unexpected, compared to conventional “solid” caps, that is to say, caps without pads, are that the damping properties of a cap comprising such pads are significantly better for equivalent total thickness. For example, the acceleration measured in the area of the head, following an impact on the crown portion, is lower by at least 15% between a cap with pads and a cap without pads.

Thus, the pads 133 act as impact absorbers (crash box) in a manner similar to car bumpers. The kinetic energy generated by the impact is thus dissipated by these pads in addition to the inherent absorption in the material of the cap. This double dissipation improves damping, compared to a cap with no pads of equivalent thickness.

Therefore, the damping mainly results from the deformation of the pads 133 and slightly via the thickness of the first layer 132. The first layer is primarily used to create a unitary structure by connecting the pads to one another.

In these examples, the height “h” to thickness “e” ratio is greater than one. Good damping results are obtained with a thickness “e” between 1.0 and 17.5 millimeters and/or with a height “h” between 10 and 35 millimeters, it being necessary to follow the previously defined ratio. For comfort, the total thickness “T” of the cap can be less than 40 millimeters.

Similarly, the average cross section of the pads is advantageously between 0.5 and 5.0 square centimeters. With a small cross section, the pad deforms more easily along a non-axial direction. With a larger cross section, the pad deforms less along a non-axial direction. However, the top 1331 of the pad has a greater surface of contact with the skull, which is more comfortable because the stress transmitted is less. A good compromise is a cross section between 1.0 and 4.0 cm².

According to a particular embodiment, the first layer 132 has a small thickness “e” of less than 10 millimeters. This small thickness makes it possible to easily conform the shape of the cap to that of the outer shell, while favoring damping pads having substantial height. In addition, the reduced thickness of the first layer and the spacing of the pads make it possible to reduce the amount of the efficient and necessary damping material. Consequently, this makes it possible to lighten the helmet, which is a very important, even fundamental, element for a sports helmet. It has been noticed that, contrary to conventional helmet constructions, it is not necessary to have a continuous thickness over the entire surface of the cap to obtain a good level of protection.

The cap is a “monolithic” element in the sense that the first layer 132 and the pads 133 form a single unitary piece. However, the cap can be constructed in several portions, each comprising a first layer and projections. By being made of a single piece, the implementation of the cap is greatly simplified. Furthermore, the number of constituent elements of the helmet is reduced, compared to a helmet provided with a number of attached pads.

To further simplify the construction of the cap, the pads are designed so that the cap can be removed from the mold by a simple movement of the tooling. This means, in this example, that the pads are oriented such that their height extends substantially along a vertical direction.

Due to the invention, the cap can be made using an economical material, such as EPS and/or EPP, taking advantage of its damping properties. Due to the recess of the inner envelope of the cap, resulting from the use of pads, the volume of the material of the cap and, therefore, the weight of the helmet, are reduced. This reduction in weight provides wearing comfort to the user without sacrificing the required safety. The reduction in the damping material is then compensated for by the potential deformation of the pads.

In this example, the top 1331 of the pads 133 is designed to be in contact with the head or an inner cap covering the head. Generally, helmets incorporate an inner cap forming the interface between the head of the user and the cap. This provides greater comfort because the cap can be made of a material more pleasant to the touch. Moreover, this enables the inner cap to easily be replaced if damaged, for example, by prolonged contact with perspiration.

In the illustrated embodiment, the pads are solid. Alternatively, one can provide to recess the pads to further lighten the structure. In this case, the cap would be comprised of hollow pads.

In summary, the pads 133 of the upper portion 131 of the cap fulfill two main functions, including impact absorption, on the one hand, and ventilation of the skull, on the other hand.

The invention is not limited to these particular embodiments. And it is possible to combine these embodiments.

Also, the invention is not limited to the embodiment described above, but extends to all embodiments covered by the following claims.

Further, at least because the invention is disclosed herein in a manner that enables one to make and use it, by virtue of the disclosure of particular exemplary embodiments of the invention, the invention can be practiced in the absence of any additional element or additional structure that is not specifically disclosed herein. 

1. A helmet comprising: an outer shell; a cap, comprising EPS or EPP, arranged inside the outer shell and having an upper portion designed to cover at least a crown portion of a wearer's head, the cap comprising: a first layer having thickness covering substantially the upper portion; and a plurality of pads having a height projecting from the first layer in a direction away from the outer shell, the first layer and the pads forming a single piece; the pads having a height greater than a thickness of the first layer.
 2. A helmet according to claim 1, wherein: the thickness of the first layer is between 1.0 mm and 17.5 mm.
 3. A helmet according to claim 1, wherein: the thickness of the first layer is less than 10 mm.
 4. A helmet according to claim 1, wherein: the height of the pads in the upper portion of the cap is between 10 mm and 35 mm.
 5. A helmet according to claim 1, wherein: an average cross section of the pads is between 0.5 mm² and 5.0 mm².
 6. A helmet according to claim 1, wherein: a plurality of the plurality of pads of the upper portion of the cap are dimensioned such that their height is greater than a smallest dimension of an average cross section of the plurality of pads.
 7. A helmet according to claim 1, wherein: a first plurality of the plurality of pads are dimensioned and arranged for axial compression along a height of the pads in response to an impact; and a second plurality of the plurality of pads are dimensioned and arranged to be deformed in a non-axial direction.
 8. A helmet according to claim 7, wherein: the second plurality of the plurality of pads are dimensioned and arranged to buckle or bend in the non-axial direction
 9. A helmet according to claim 1, wherein: the pads are distributed randomly in the upper portion of the cap.
 10. A helmet according to claim 1, wherein: tops of the pads are designed to be in contact with the wearer's head or an inner cap covering the wearer's head.
 11. A helmet according to claim 1, wherein: the pads have a substantially parallelepipedic shape.
 12. A helmet according to claim 1, wherein: the cap is a unitary piece.
 13. A helmet according to claim 1, wherein: a plurality of the plurality of the pads have respective bases; and a cross section of each of the bases is substantially the same as respective cross sections of tops of the pads.
 14. A helmet according to claim 1, wherein: the plurality of pads are oriented such that their height extends substantially along a vertical direction.
 15. A helmet according to claim 1, wherein: the cap is a molded cap.
 16. A helmet according to claim 1, wherein: the plurality of pads are recessed. 